Electrical relay



July 11, 1944. P, H 'CRAGO l2,353,392

- ELECTRICAL RELAY Filed June 13, 1942 fz'yl.

HISTTUHA/EY.

Patented `Iuly 11, 1944 ELECTRICAL RELAY Paul H. Crago, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application June 13, 1942, Serial` No. 446,967

7 Claims.

My invention relates to electrical relays, and particularly to electrical relays of the direct current type having both a polar and a neutral armature. More particularly, my invention relates to relays of this type which are provided with two separate energizing windings one of which is supplied with currentto cause the polar armature to assume its one operated position, and the other of which is supplied with current to cause the polar armature to assume its other operated position.

For certain circuit applications it is desirable to render the neutral armature of a relay of the type described slow releasing without affecting its pick-up time, and one object of my invention is to provide novel means for accomplishing this desirable result. n l

According to a preferred form of my invention, I provide each energizing winding with a shunt circuit including a iront neutral contact of the relay and an asymmetric unit. `These shunt circuits are so arranged that when either energizing Winding becomes energized, the associated asymmetric unit willact to prevent the other winding from becoming energized, but that when either windingY becomes deenergized, the associated asymmetric unit will permit the current-induced in such winding by the decaying ux to -ow in the associated shunt circuit and thus delay the decay of the flux to thereby de lay the release of the neutral armature. Since the shunt circuits are open when the neutral armature is picking up, they have no effect on the pick-up time of the neutral armature.

When the degree of retardation of the neutral armature need not be great, a high resistance may be employed in the shunt circuits in place of the asymmetric units.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

I shall describe two forms of relays embodying my invention, and shall then point out the novel features thereof in claims. f

In the accompanying drawing, Fig. 1 is a View, partlydiagrammatic, showing one form of relay embodying my invention. Fig.` 2 is a view similar to Fig. 1 showing a modied form of relay embodying my invention, l

Similar reference characters refer to similar'v parts in both views.

Referring iirst to Fig. l., the relay PR. here illustrated comprises a neutral magnet N and a polar magnet P. The neutral magnet N ineludes, as usual, a pair of magnetizable cores I and 2 connected at one end by a magnetizable backstrap 3 and provided at the other end with enlarged pole pieces la and 2a. The magnet N controls a neutral armature 6, and is provided with two separate energizing windings, one of which `comprises two series connected coils 4a and 1b disposed respectively on the cores l and 2, and the other of which comprises two series connected coils 5a and 5b disposed respectively on the cores i and 2. The armature 6 is pivotally supported at for swinging movement toward and away from the pole pieces la and 2a, and is operatively connected with a plurality of contact fingers 6 and S which cooperate respectively with iixed front contact members 8a and 9a, or xed baci: contact members 8b and 9b to close front neutral contacts S-Sa and S-Sa or back neutral contacts 8-Sb and 99b according as the neutral armature 6 is swung toward or away from the pole pieces la and 2a.

The energizing winding comprising the coils 5a and 5b is provided with an energizing circuit which is supplied with current from the terminals B and C of a suitable source not shown over the front contact lll-Illa of a relay A and a front contact i a relay D, and the energizing winding comprising the coils 4a and 4b is similarly provided with an energizing circuit which is supplied with current from the terminals B and C over the back contact lll--lllb of relay A and front contact I5 of relay D. The two energizing windings are so arranged in these circuits that when the rst mentioned circuit is closed, the magnet N will be supplied with flux of what I shall term norma polarity, and that when the second mentioned circuit is closed, the magnet N will be supplied with flux of what I shall term reverse polarity. It will be obvious, of course, that when either one of these energizing circuits is closed, the neutral armature will be attracted toward the pole pieces la and 2a..

The polar magnet P as here shown is in the form of a permanent magnet the upper end of which is connected with the backstrap 3 and the lower end of which is provided with an enlarged pole piece Il. This magnet might, however, equally well comprise a magnetizable core rprovided with a constantly energized winding, as is well understood. The polar magnet P cooperates with a polar armature l2 which is .pivotally mounted at I3 adjacent the pole piece Il for swinging movement toward one or the other of the pole pieces la or 2a according as the neutral magnet N is supplied with flux of normal or reverse polarity. Operatively connected with the polar armature I3 is a polar contact nger lll which cooperates with a fixed contact iinger lila to close a normal contact l4|4a when the polar armature is swung toward the pole piece la, and which cooperates with a xed contact ringer |417 to close a reverse contact M-Hb when the polar armature is swung toward the pole piece 2a.

The portion of the relay thus far described is well known, and its operation will be readily understood from the foregoing without further detailed description.

For certain circuit applications it is desirable to delay or retard the release of the neutral armature of a relay of the type described without affecting its pick-up time. According to my present invention, I accomplish this result by providing each energizing winding with a unidirectional shunt circuit which is closed only when the neutral armature occupies its attracted position. The shunt circuit for the energizing winding comprising the coils 4a and 4b includes front neutral contact S-Sa and an asymmetric unit RI, while the shunt circuit for the energizing winding comprising the coils 5a and 5b includes front neutral contact 99a and an asymmetric unit R2. Since these shunt circuits both include front contact 9--9a, it will be apparent that they will become closed when and only when the neutral armature 6 is moved toward the pole pieces la and 2a to its picked-up or attracted position. The asymmetric units are so arranged in these circuits that when either energizing winding becomes energized, the asymmetric unit associated with such winding will block the flow of current t0 the other winding through the two asymmetric units in series, but that, when either winding becomes deenergized, the associated asymmetric unit will permit the current induced in such winding by the decaying flux to Iiow in the associated shunt circuit and will thus delay the decay of the ux, whereby the release of the neutral armature is delayed. Inasmuch as the shunt circuits are open at front contact B-Qa when the neutral armature is picking up, it will be obvious that these circuits have no effect on the pick-up time of the neutral armature.

As shown in the drawing, the relays A and D are both deenergized, and both energizing circuits for relay PR are therefore open. Under these conditions, the neutral armature 6 occupies its open or released position, and the polar armature I2 is held by flux from the permanent magnet in its last energized position which is illustrated as its reverse position. With neutral armature -6 in its released position, the neutral back contacts 8-8b and 9-912 are closed and the neutral front contacts 8-8a and S-Qa are open, and with polar armature l2 in its reverse position reverse contact lll- Mb is closed and normal contact l4--l4a is open. Since contact S-Ba is open, the shunt circuit for each of the energizing windings is open.

I shall now assume that with relay A in its deenergized position relay D becomes energized. This will complete the energizing circuit for the winding comprising coils 4a and 4b, which will cause the neutral armature 6 to pick up, but will not cause operation of the polar armature. Since both shunt circuits are open while armature 6 is picking up, these circuits will not affect the pick-up time of this armature and this armature will therefore pick up quickly. However, as soon as armature 6 picks up, the shunt circuit for the winding comprising the coils 4a and 4b will become closed, and as a result, if relay D now becomes deenergized for any reason, armature 6 will be rendered slow releasing. By proper proportioning of the parts, this release time can be made sufficiently slow so that if relay D is only momentarily deenergized, armature 6 will remain in its attracted position.

If relay A becomes picked up when relay D is energized, the winding comprising the coils 4a and 4b will become deenergized and the winding comprising the coils 5a and 5b will become energized. This will cause the flux induced in magnet N to reverse, and as a result polar armature l2 will reverse and armature -6 will release and then again pick up. The release of armature 6, however, as well as the reversal of the polar armature |2 will be delayed somewhat due to the shunt circuits for the windings 4a and 4b, but the open circuit time for the neutral front contacts will be the same as if both shunt circuits were not provided since after armature B has once started to release, it will release and pick up quickly. It should be noted, however, that while the release of armature `l will be slowed up somewhat under these conditions it will not be slowed up as much as when the energizing circuit for either of the windings is merely opened because the decay of the flux will be accelerated by the opposing flux set up by the energization of the windings 5a .and 5b.

If relay A becomes deenergized while relay D is energized, the operation will be just the reverse of that just described, as will be readily under- StOOd.

' ing up in the cores of magnet N would cause a current to flow in the shunt circuit for such other winding, which current would oppose the growth of the iiux and thus delay the pickup of the neutral armature. With this contact included in these circuits, however, this undesirable result is prevented.

When the degree of slow release of the neutral armature need not be great, the asymmetric units RI and R2 can be replaced by relatively high resistances Xl and X2, as shown in Fig. 2. In this event there will of course be two paths for current to flow when either energizing circuit becomes closed. For example, when the energizing circuit for the winding including the coils la and 4b becomes closed, a branch path will be closed through the resistances XI and X2 and the coils 5a and 5b to terminal C. Since the energization of the coils 5a and 5b under these conditions will be in the same direction as when the normal energization circuit for these windings is closed, it will be obvious that the eiect of this branch path will be to tend to decrease the eiective magnetization of the cores, and as a result this arrangement is less efficient than that shown in Fig. l. The branch path which will be closed when the energizing circuit for the winding including the coils 4a and 4b becomes closed will be obvious from an inspection o the drawing.

In case the release time desired is only that required to bridge the interval which elapses between the opening of the front contacts and the closing of the back contacts or vice versa of a standard neutral relay, the resistances Xl and X2 may be of such a value that the energizing winding which is then effective to energize the magnet N will receive 8O per cent or thereabout oi the energy it would receive if there were no leakage through the resistances.

The arrangement including the two resistances Xl and X2 is advantageous where there is danger of alternating current being induced in one or the other of the energizing circuits because there is less likelihood of the induced current tending to hold up the neutral armature when the circuit is interrupted at contact I of relay D.

Although I have herein shown and described only two forms of relays embodying my invention, it is understood that various changes and modiiications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. A relay comprising a neutral magnet, two separate windings one for setting up flux ci one polarity and the other for setting up llux of the other polarity in said neutral magnet, a neutral armature responsive to the presence or absence ci flux in said neutral magnet, a polar armature associated with said neutral magnet, means for setting up a polarizing lluX in said polar armature to cause it to respond to the polarity of the flux set up in said neutral magnet by said win-dings, and means for delaying the release but not the pick-up of said neutral armature comprising two aunt circuits one for each of said windings and each including the same contact controlled by said neutral armature and closed only when said neutral armature has responde-d to the presence of flux in said neutral magnet.

2. A relay comprising a neutral magnet, two separate windings one for setting up flux of one polarity and the other for setting up flux of the other polarity in said neutral magnet, a neutral armature responsive to the presence or absence of ilux in said neutral magnet, a polar armature associated with said neutral magnet, means for setting up a polarizing ilux in said polar armature to cause it to respond to the polarity of the Iflux set up in said neutral magnet by said windings, a contact closed when either of said windings is energized, and two shunt circuits each including said contact, a different one of said windings and means for blocking the flow of current to the other winding when the associated winding is energized while permitting the iiow of induced current in the associated winding when it becomes deenergized.

3. A relay comprising a neutral magnet, two separate windings one for setting up flux of one polarity and the other for setting up ilux of the other polarity in said neutral magnet, a neutral armature responsive to the presence or absence of ilux in said neutral magnet, a, polar armature associated with said neutral magnet, means for setting up a polarizing flux in said polar armature to cause it to respond to the polarity of the flux set up in said neutral magnet by said windings, a contact closed when either of said windings is energized, and two shunt circuits one for each winding and each including said contact for delaying the release of said neutral armature when either winding becomes deenergized.

4. A relay comprising a neutral magnet, two separate windings one for seting up flux of one polarity and the other for setting up flux of the other polarity in said neutral magnet, a neutral armature responsive to the presence or absence of flux in said neutral magnet, a polar armature associated with said neutral magnet, means for setting up a polarizing ux in said polar armature to cause it to respond to the polarity of the flux set up in said neutral magnet by said windings, a Contact closed when either of said windings is energized, and two shunt circuits one for each winding each including some resistance and said contact, said circuits being effective to retard the decay of ux when either winding becomes deenergized.

5. A relay comprising a neutral magnet, two separate windings one for setting up ilux of one polarity and the other for setting up flux of the other polarity in said neutral magnet, a neutral armature responsive to the presence or absence of flux in said neutral magnet, a polar armature associated with said neutral magnet, means for setting up a polarizing iiux in said polar armature to cause it to respond to the polarity of the ux set up in said neutral magnet by said windings, a contact closed when either of said windings is energized, two asymmetric units, and two shunt circuits one for each winding and each including said contact and a diierent one of said asymmetric units poled to permit induced current to flow in the associated winding upon deenergization of the winding.

6. A relay comprising a neutral magnet, two separate windings one for setting up iluX of one polarity and the other for setting up flux of the other polarity in said neutral magnet, a neutral armature responsive to the presence or absence of flux in said neutral magnet, apolar armature associated with said neutral magnet, means for setting up a polarizing ilux in said polar armature to cause it to respond to the polarity of the flux set up in said neutral magnet by said windings, a contact closed when either of said windings is energized, two asymmetric units, and two shunt circuits one for each winding and each including said contact and a diierent one of said asymmetric units, the asymmetric units being so arranged in said shunt circuits that when either energizing winding becomes energized the asymmetric unit associated with such winding will block the now of current to the other winding through the other asymmetric unit but that when either winding becomes deenergized, the associated asymmetric unit will permit the current induced in such winding by the decaying ux to flow in the associated circuit, whereby the release of said neutral armature is delayed.

7. A relay comprising a neutral magnet, two separate windings one for setting up flux of one polarity and the other for setting up flux of the other polarity in said neutral magnet, a neutral armature responsive to the presence or absence of flux in said neutral magnet, a polar armature associated with said neutral magnet, means for setting up a polarizing ux in said polar armature to cause it to respond to the polarity of the flux set up in said neutral magnet by said windings, a contact closed when either of said windings is energized, two resistances, and two shunt circuits one for each winding and each including said Contact and a different one of said resistances.

PAUL H. CRAGO. 

